Fisheries biologists in Montana and Idaho are once again turning their attention to the spring breeding habits—or lack thereof—of the dwindling Kootenai River white sturgeon population. But four years into a critical habitat designation that stipulated Libby Dam be managed for sturgeon recovery, it looks like the fish might not need much help getting down to business this year.
The erection of Libby Dam in 1974 radically reduced spring flows on the Kootenai River, making it difficult for white sturgeon to reach gravel spawning beds upstream of Bonner's Ferry, Idaho. Sturgeon numbers have since plummeted by an estimated 9 percent annually. The federal government listed the population as endangered in 1994, and biologists believe that unless wild sturgeon start reproducing soon, fewer than 30 spawning fish will remain by 2015.
Last year, the U.S. Army Corps of Engineers conducted its first spill test at Libby Dam to increase flows and coax sturgeon farther upstream. Now it looks like year two won't happen. Snowpack in the Kootenai River basin is way above average this year, according to the National Weather Service, so the Corps will blend sturgeon management into its flood control operations as the Kootenai continues to rise.
"This is not something we'd be able to physically do in most years, even with flow augmentation," says Brian Marotz, a hydropower mitigation coordinator with Montana Fish, Wildlife and Parks. The data Marotz hopes to collect during such an unusual year could also shed light on the importance of water temperature to sturgeon.
The Corps has been reluctant to accommodate white sturgeon in the past by releasing water from Lake Koocanusa, Libby Dam's reservoir, prompting the Center for Biological Diversity to sue it three times. A federal critical habitat declaration on the Kootenai River in 2008 made spill tests like the one last year a requirement for the Corps' management of Libby Dam.
Marotz says last year's spill test failed to encourage spawning females upstream. He remains hopeful that this year, nature will be a more successful aphrodisiac.